Method and device for determining the alcohol content of a person&#39;s breathing

ABSTRACT

A method of determining the alcohol content of air exhaled by a person using a flow through testing tube having an alcohol indicating material therein and a sampling tube to which the air is directed which has a material therein for retaining the alcohol of the breathing air and also using a suction pump comprises cooling the sampling tube, passing the exhaled air through the cooled sampling tube, measuring a volume of the air passing through the cooled sampling tube, heating the sampling tube and connecting the suction pump to the sampling tube to suck flushing air through the heated tube and then through the testing tube. The sampling tube advantageously contains a silica gel to retain the alcohol therein. The volume measuring device may be a measuring bag.

FIELD AND BACKGROUND OF THE INVENTION

This invention relates in general to breath testing devices and inparticular to a new and useful apparatus and method for determining thealcohol content of exhaled air.

Breath alcohol testers must be easy to carry by the user and be able tobe applied immediately. The test result should be sufficiently accurate,despite the often adverse circumstances under which the test must beperformed, also in the open. The often lacking willingness of the testperson to cooperate must not affect the test result.

In one known breath alcohol tester the test person blows directlythrough a test tube via a mouthpiece. The parameter "exhaled amount ofgas", required to determine the alcohol concentration in the exhaledair, is found by means of a measuring bag which follows the test tubeand must be inflated. This known method required test tubes of lowresistance to keep the blowing effort of the test person within limits.Therefore, the breath alcohol test tubes must be of relatively largesection and can have a relatively short preparation layer only. Sincethe length of discoloration of the reagent preparation is the measure ofthe alcohol content in the exhaled air, a prolongation would be in thesense of a greater measuring sensitivity, (DE-PS No. 10 52 630).

One known device to measure the exhaled gas mixture by means of a breathalcohol test tube has a breath sampling chamber of a defined maximumvolume. It is brought, by the breath blown in, from a starting positioninto an end position so that it contains a breath sample of a definedvolume. When the breath sampling chamber is filled, a pump is actuatedwhich conducts the breath contained in the breath sampling chamber toand through the breath alcohol test tube via a line. Conducting thebreath through the breath sampling chamber leads to difficulties onaccount of cooling. To prevent this, the entire device, not only thechamber but also all lines, is heated. This makes the devicecomplicated, bulky and, fundamentally, requires the warm-up periodbefore use (DE-PS No. 12 98 311).

The length of discoloration being the measure of the alcohol content inthe exhaled air, lengthening it would produce a greater measuringsensitivity. The test tube employed to analyze the air at work stationsare used in conjunction with a gas sensing pump. With it, greater flowresistances in the test tube can be overcome. These standard test tubesare of smaller diameter, from which then follows a longer reagentlength, which is totally in the sense of the desired extension of thediscoloration.

SUMMARY OF THE INVENTION

The invention provides a breath alcohol test method and device usingalcohol test tubes, which requires no blow effort from the test personand yet furnishes sufficiently accurate test results.

In accordance with the invention exhaled air is directed through a tubewhich is placed in a cooler and the alcohol content of the air isretained in a silica gel contained in the tube. The air is directed intoa volume measuring device. Thereafter the sampling tube is heated and aflushing air is directed through the sampling tube and the silica geltherein and into an alcohol test tube.

This makes it possible in an advantageously simple manner, using alcoholtest tubes, to carry out exact, quantitative breath alcohol analyseswithout overstressing the test person by too great a test tuberesistance. With a cooled sampling tube of little resistance the alcoholis stored in a first step without exertion on the part of the testperson and, independently thereof, the alcohol content is thendetermined in a second step from the heated sampling tube by means of agas sensing pump and a standard test tube. The method presents noproblems in its execution because, except for some connectors, nocomponents other than the known ones are required.

Accordingly it is an object of the invention to provide a method ofdetermining the alcohol content of air exhaled by a person using a flowthrough testing tube having an alcohol indicating material therein andalso a sampling tube to which the air is directed which has a materialtherein for retaining the alcohol of the breathing air, comprisingcooling the sampling tube as the exhaled air is directed through thesampling tube and into a measuring device until a predetermined quantityof air has been collected, thereafter heating the sampling tube andpassing a flushing air through the tube and through the alcohol testingtube in order to obtain an indication of the alcohol present therein.

A further object of the invention is to provide a device for testing aperson's breath for the presence of alcohol which comprises a samplingtube having silica gel therein which is connectable to a measuringdevice for the passage of a predetermined quantity of air therethroughwhile the tube is being cooled and which also includes heater means forheating the tube after a selected volume of breathing air is passedtherethrough so as to flush the alcohol from the material retaining thealcohol in the tube into an alcohol testing tube to indicate the alcoholpresent.

A further object of the invention is to provide a device for determiningalcohol content of a person's exhaled air which is simple in design,rugged in construction and economical to manufacture.

The various features of novelty which characterize the invention arepointed out with particularity in the claims annexed to and forming apart of this disclosure. For a better understanding of the invention,its operating advantages and specific objects attained by its uses,reference is made to the accompanying drawings and descriptive matter inwhich preferred embodiments of the invention are illustrated.

BRIEF DESCRIPTION OF THE DRAWINGS

In the Drawings:

FIG. 1 is a schematic sectional view of a sampling tube and volumemeasuring device for use in obtaining a sample of exhaled air; and

FIG. 2 is a view similar to FIG. 1 showing the sampling tube position inwhich it is used for directing the flushing air through the alcoholretaining material and into an alcohol testing tube.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings in particular, the invention embodied thereincomprises an apparatus and method for testing for alcohol content inexhaled air 1 which is directed in a first step through a sampling tube2 which is arranged in a cooler so that it is cooled. In addition, thesampling tube contains a silica gel 2a which retains alcohol of theexhaled air. The exhaled air 1 is directed through the tube 2 in aquantity to produce a predetermined volume which is measured by a volumemeasuring device 3.

After the initial volume is obtained, flushing air is directed throughthe tube 2 when the tube is being heated in a heater 8. This flushingair passes through the silica gel 2a and through an alcohol test tube 4where the alcohol is indicated.

The method according to the invention is shown schematically in thedrawing.

It shows these steps:

1. Sampling according to FIG. 1.

2. Analysis according to FIG. 2.

Within the scope of sampling per step 1, the exhaled air 1 to be testedfor alcohol is blown by lung power at arbitrary velocity through asampling tube 2 which is filled with silica gel 2a and cooled by acooler 7 to about 0° to 5° C., and the amount of exhaled air blownthrough it is determined in the process in a succeeding volume measuringdevice 3. The flow resistance of the sampling tube 2 is low. While theexhaled air flows through it, the alcohol content is retained in thesampling tube filling 2a.

After sampling is concluded and after the respective exhaled volume hasmoved through the sampling tube 2, the tube is removed from the cooler 7and, as step 2, exposed to a heater 8 while being attached at the sametime to an alcohol test tube 4 having a material therein which indicatesalcohol present and relative amount. This involves a standard test tubeto be used with a gas sensing pump.

The measurement starts at a temperature of 150° to 200° C. in thesampling tube 2. Flushing air 5 is sucked by the gas sensing pump 6first through the sampling tube 2 and then through the alcohol test tube4 for this purpose. The discoloration in the alcohol test tube 4 is themeasure of the alcohol content in the exhaled air.

While specific embodiments of the invention have been shown anddescribed in detail to illustrate the application of the principles ofthe invention, it will be understood that the invention may be embodiedotherwise without departing from such principles.

What is claimed is:
 1. A method of determining the alcohol content ofair, exhaled by a person, of the type in which a flow of the exhaled airis passed through a sample tube which has a silica gel therein forretaining the alcohol in the air, comprising cooling the sample tube andsilica gel to a temperature of 0° to 5° C., directing exhaled airthrough the cooled tube and the alcohol retaining silica gel whilemeasuring the air which passes through the sample tube to obtain apredetermined volume, and subsequently heating the sample tube andsilica gel to a temperature of 150° to 200° C., and then directing aflushing air therethrough at a temperature of 150° to 200° C.